Hello Paul,
Yes, correct. I followed those instructions first. Initially I assumed Xojo (obtained via the Ubuntu Software Center) installed multi arch thinking that Xojo itself is 32 bit, but then went the route of installing multiarch anyways. Buttons, windows, text boxes, etc. appear to work. Console apps as well. But HTMLViewer throws the given error.
Let’s have a try with:
sudo apt-get install libwebkitgtk-1.0.0:i386The :i386 should tell your Linux system to install the 32-Bit version of the lib(s).
I wish it were that easy. It appears to want to install a longer list of :i386 dependencies that go above and beyond simple multi arch support. I lost count and after a dozen more packages and still no go. 
Ahh well. I appreciate Xojo’s cross-platform-ness, at least for the CLI. It’s attempts for UI are noble. I’ve gone ahead and implemented nodewebkit and I guess it’s a good thing I’m seasoned in CSS and HTML standards as that appears to work out beautifully. It’s not hard to know markup by any stretch. I’ll just have to port my logic to more CLI modules in a background process. Not what I set out for initially, but way more ubiquitous. Problem solved.
I know, not the best solution, but anyone tried to use the 'Microsoft WebBrowser ActiveX with an OLEContainer in Xojo for a workaround yet? Is it worth it?
Thinking of creating a new Class in Xojo to implement a superclass and later - when Xojo gets stuff fixed with 64bit Linux hint hint - change this Superclass to standard HTMLViewer-Class again.